Read the Key Clinical Research

FOR THOSE WHO LIKE A LITTLE MORE DETAIL HERE ARE SOME  KEY CLINICAL RESEARCH PAPERS WHICH INDEPENDENTLY SUPPORT THE SAFETY AND EFFECTIVENESS OF OVERNIGHT VISION CORRECTION/ORTHOKERATOLGY  CONTACT LENS TREATMENT

Below is a link to the original FDA approval for the i-GO lens manufactured by Euclid Systems under its US name "Emerald" 

Studies have shown that complications from myopia, such as chorioretinal degeneration and retinal detachment will increase with increasing myopia. The application of corneal reshaping or orthokeratology may potentially stabilize the progressive nature of myopia throughout the adolescent years. Additionally, if wearing corneal reshaping lenses controls the progression of myopia, there also may be a reduction in the rates of adverse effects of advancing myopia. The fact that myopia is on the rise indicates that although the wearing of spectacles clears the vision, it does nothing to control the progression of myopia and its adverse effects.

Conclusions: The initial recruitment phase, fitting statistics, and demographics provide the structure for the five year SMART investigation. Initial dispensing data for corneal reshaping test subjects showed a high first lens success rate to achieve 20/20 unaided acuity. Long term results of this study will provide fitting information, myopia progression comparative data, anatomical differences, and subjective responses to each lens modality. 80.5% of the test group were fit able to use the initial empirically fit lens and did not require a lens change. 

Two studies in the past twenty years have shown that rigid gas permeable contact lenses slow the progression of nearsightedness in children, however both studies failed to provide proper attention to many important variables. While these earlier works produced intriguing results for scientists and clinicians, they contain many problems that challenge the significance of the studies findings. The faults of the previous studies can be summarized in four categories: 1) high losses to follow-up, 2) inadequate control group, 3) incomplete ocular component measurements, and 4) inadequate or poorly selected entry criteria. Positive results in previous studies also failed to exclude alternate possibilities which may explain why rigid gas permeable contact lenses may slow the progression of myopia.

For example, the studies found that rigid contact lenses slow the progression of myopia and that corneal flattening accounts for some of the treatment effect, but none of the studies was able to definitively answer other mechanisms that may slow myopia advancement. A need for a controlled study of rigid contact lenses which measures all of the components that may affect myopia progression still exists. The CLAMP Study examines all of these components and addresses the problems encountered in previous studies. The CLAMP Study uses a run-in period to enroll only children who are able to adapt to rigid contact lens wear into the study. This decreases the number of children who drop-out of the study because they cannot adapt to rigid contact lens wear. Once children show that they are able to wear rigid contact lenses, they are enrolled in the study and randomly assigned to wear rigid gas permeable contact lenses or soft contact lenses. Both groups are then examined each year for three years to determine which group progresses the most in nearsightedness.

Annual examinations include assessment of the children's ability to focus their eyes, their eye glass prescription, the length of their eyes, detailed maps of the shape and thickness of their corneas (the clear window on the front of the eye), the shape of their eyes, and the curvature of the lens inside the eye. Their eye glass prescription is determined when the children's eyes are dilated. We examined 222 children for eligibility. Out of the 222 children, 148 were eligible to participate in the run-in period. Of the 148 eligible children, 116 (78.5%) were able to adapt to rigid gas permeable contact lens wear. All of the children were examined at The Ohio State University College of Optometry. 

Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan  thiraoka@md.tsukuba.ac.jp

Methods: Seventeen subjects undergoing orthokeratology for 12 months were examined. Refraction, corneal topography, wavefront aberrometry, a visual acuity test and a contrast sensitivity test were performed at baseline, 12 months after commencement of the procedure, and 1 week and 1 month after discontinuation of the treatment. Asymmetry and higher-order irregularity components were calculated using a Fourier analysis of the corneal topography data. Contrast sensitivity was assessed at four spatial frequencies, and the area under the log contrast sensitivity function (AULCSF) was calculated.

Results: Orthokeratology significantly reduced manifest refraction (p<0.0001, Dunnett test) and significantly improved uncorrected visual acuity (UCVA) at 12 months after commencement of the procedure (p<0.0001). Asymmetry and higher-order irregularity components increased significantly (p<0.0001, p = 0.0032, respectively), and third- and fourth-order aberrations also increased significantly (p<0.0001). The treatment resulted in significant decreases in AULCSF (p = 0.0004). After discontinuing lens wear, all parameters, such as refraction, UCVA, asymmetry, higher-order irregularity, third-order aberration, fourth-order aberration and AULCSF, returned to the baseline level at 1 week.

Conclusion: This study confirmed that the effect of orthokeratology is completely reversible in light of optical quality of the eye and quality of vision as well as refraction and visual acuity.

Postortho-k uncorrected VAs were significantly correlated with the residual overall blurring strength (length of the vector representing the residual refractive error) in both eyes at all contrast levels. The mean postortho-k uncorrected VA in the better eye were 0.00 +/- 0.11, 0.08 +/- 0.11, 0.21 +/- 0.12, and 0.46 +/- 0.13 with the 90%, 48%, 21%, and 7% contrast charts, respectively. These were comparable to the best corrected VA of the better eye of the control group with the 90% (-0.03 +/- 0.07) and 48% contrast charts (0.03 +/- 0.09), but worse than those of the control group with the 21% (0.13 +/- 0.10) and 7% (0.35 +/- 0.13) contrast charts. Postortho-k VA, with the four different contrast charts, improved by 0.07 to 0.12 log units in the better eye and 0.15 to 0.18 log units in the worse eye after correction of the residual refractive error; the improved VA was comparable to the best corrected VA of the control group.

Onset of the effects of overnight OK lens wear is rapid, with most change after the first night of lens wear and stability of refractive change after seven to 10 days. Mean reductions in myopic refractive error of between 1.75 and 3.33 D and individual reductions of up to 5.00 D have been reported. There appear to be slight reductions or minimal changes in astigmatism with the use of reverse-geometry lenses and most patients are reported to achieve 6/6 unaided vision or better. The induction of higher order aberrations, in particular, spherical aberration, has been reported and this may affect subjective vision under conditions of low contrast and pupil dilation. Patient satisfaction with overnight OK has been reported as similar to or better than with other popular modalities of contact lens wear.

Method. Normal ocular flora of 41 subjects was determined twice before commencing ortho-k lens wear by culture of the lower conjunctiva. Further specimens were collected on six follow-up visits after beginning lens wear, as were samples from their lenses, cases, and suction holders. A questionnaire on lens care was administered after the fifth visit. Results. Three subjects provided conjunctival samples yielding Staphylococcus aureus on one occasion before lens wear, one being positive for this organism after beginning lens wear. Of 38 subjects yielding no growth or only normal eye flora before use, 28 remained free of ocular pathogens after beginning lens wear. Only four subjects had positive cultures on more than one occasion after lens wear. There was no significant difference in isolation levels of pathogens with lens wear (p = 0.423) culture of 54% of subjects yielded no growth or normal flora only; lenses of 16 subjects yielded potential pathogens, including three subjects contaminated on more than one occasion. Lens isolates did not match the organisms transiently colonizing the eye. Lens case, the most frequently contaminated item, was associated with lens contamination (p < 0.001), the same organism being isolated from both items in 11 subjects. Lens suction holder was less frequently contaminated.Neither lens case nor suction holder contamination was associated with isolates from the eye. Reported good compliance correlated with lack of contamination in all but one subject. The most frequent breaches in the lens care protocol were failure to clean, disinfect, and replace the lens case.

Conclusion. Ocular flora was not altered by ortho-k lens wear over an extended period, and patients remained free of infection. Contaminants identified were generally of a transient nature.Most patients had significant contamination of at least one item, most frequently the lens case. Lens case isolates were significantly associated with those from the lens. The majority of patients reporting good compliance had low or no contamination of their lenses and accessories. (C) 2005 American Academy of Optometry 

Methods. Twenty-nine 8- to 11-year-old children with myopia between -0.75 and -5.00 D and <-1.50 D corneal toricity were fitted with corneal refractive therapy contact lenses (Paragon Vision Sciences, Mesa, AZ). They were examined within 1 hour of awakening and about 6 hours later at 1 day, 1 week, 2 weeks, 1 month, 3 months, and 6 months after the first night of contact lens wear. At each visit, the logarithm of the minimum angle of resolution (logMAR) visual acuity, manifest refraction, slitlamp examination, and corneal topography were performed.